Vertical or horizontal - for Sound Check Plasterboard

<div>I will be building a long wall (5476 mm) across a living room to create a new bedroom. The tenant in there may hear noise from the (now smaller) living room, so I would like to cut the noise down. At the moment insulation batts are hard to find because of the rush to insulate (government program), but the guy at Plastamasta told me about this stuff called ‘sound blanket’, which deadens noise. He also said I could use “sound check” plasterboard, which is denser and heavier than normal plasterboard, so cuts down noise. It only comes in 3 met. lengths, and is about three dollars more than normal plasterboard.

My ceiling is 2.4 metres high, and the studs will have 600 mm centres.

On the question of hanging wallboard vertically or horizontally, most plasterers advise to hang it horizontally. In my case I have a problem though. On this long wall, if I hang the sheets horizontally, each side will have 2 butt joints and one long recessed join, adding up to about 7.9 metres. If I hang the sheets vertically, each side will have four recessed joins equal to 9.6 metres. While the vertical method will waste .6 metres with each panel (a total of 3 metres), it would have two advantages.

1) All joins will be recessed, and easier (for an amateur) to make invisible

2) It would not involve heavy lifting. I don’t know if I how easily I can lift the 3 metre horizontal sheets to place on the top part of the wall, given that they are supposed to be a lot heavier than normal, and I work on my own.

I don’t want to nail the first two horizontal sheets on, only to find that I can’t lift the last two sheets up, or to find out that the butt joints are obvious on the long wall, against the light of the window down the far end. Going vertical would cost me an extra $29.00 in wasted offcuts, but maybe it would be worth it for the recessed joins, and less heavy work?
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